1. Field of the Invention
The present invention relates to an image sensing apparatus such as a digital still camera and a digital video camera equipped with a shake correction mechanism for correcting shake of the camera, as well as a focal plane shutter to be loaded in the image sensing apparatus.
2. Description of the Related Art
Generally, in a camera provided with a focal plane shutter and an image sensor, the focal plane shutter and the image senor have arrangements as shown in FIGS. 9A and 9B. FIG. 9A is a cross-sectional view schematically showing the arrangement of the image sensor taken along a plane including an optical axis of an unillustrated imaging optical assembly, and FIG. 9B is a plan view as viewed from the direction shown by the arrow E in FIG. 9A. It should be noted that in FIGS. 9A and 9B, a low pass filter is arranged on the imaging plane of the image sensor, and the image sensor and the low pass filter constitute an imaging unit, and is called as such hereinafter.
As shown in FIGS. 9A and 9B, the focal plane shutter 2000 and the imaging unit 2001 are aligned on the optical axis L of the unillustrated imaging optical assembly in such a manner that the light receiving planes of the image sensor 2002 and the low pass filter 2003 are perpendicular to the optical axis L.
The focal plane shutter 2000 is arranged in parallel with a plane perpendicular to the optical axis L on the side of an object to be photographed with respect to the imaging unit 2001, and includes a shutter bedplate 2004, a shutter base plate 2005, and a shutter blade group 2006.
The shutter bedplate 2004 and the shutter base plate 2005 are respectively formed with openings 2004a, and 2005a, so that light passing through the imaging optical assembly is guided onto the imaging unit 2001 through the openings 2004a, 2005a. 
In the conventional focal plane shutter 2000, the opening 2005a of the shutter bedplate 2005 has a size substantially identical to an effective light receiving region for outputting pixel signals composing a sensed image. The opening 2004a of the shutter bedplate 2004 has the same size as or larger than the opening 2005a of the shutter base plate 2005.
There is known a technique of correcting shake of a digital camera by driving (oscillating) an image sensor to eliminate or suppress blur of a sensed image arising from the shake of the camera (see Japanese Unexamined Patent Publication No. 2003-222923). The publication discloses a camera equipped with actuators for driving the image sensor in one of two directions perpendicular to each other on the imaging plane of the imaging optical assembly, wherein blur of a sensed image due to shake of the camera is eliminated or suppressed by driving the image sensor in one of the two directions by the respective actuators.
A need exists for miniaturizing the camera to provide enhanced portability. There is an idea of devising a positional arrangement of the focal plane shutter 2000 and the imaging unit 2001 with respect to the optical axis direction as a means for reducing the thickness of the camera in the optical axis direction.
In the case where the shake correction based on driving of the image sensor 2002 is applied to the camera provided with the focal plane shutter, there is likelihood that light is blocked from being incident on the light receiving plane of the low pass filter 2003 by the shutter base plate 2005 in driving the imaging unit 2001 (image sensor 2002) in one of the two directions perpendicular to each other on the imaging plane of the image sensor 2002, if the opening 2005a of the shutter base plate 2005 has the size substantially identical to that of the effective light receiving region for outputting pixel signals composing a sensed image. If such a phenomenon occurs, it is likely that a properly sensed image may not be obtainable due to failure of partly receiving the light object image.